Staff: Mentor

The unique large branching fraction of N(1535) to Nη (~40%) in agreement between paper and PDG, the good agreement of the given width and the rough agreement in one quoted amplitude value (page 9) suggest they are the same particle.

Why not? It is a baryon resonance that commonly decays to those particles.

11 look like the other quantum numbers similar to a hydrogen-like atom. I don't see how a bound state of those could work, however - it would not have enough energy to decay in this way, and it should be more long-living.